1. Field of the Invention
The present invention relates to an ultra high frequency band radio communication apparatus employing a band of ultra high frequencies.
2. Description of the Prior Art
Ultra high frequency band radio communication apparatuses are known as using a milliwave band or quasi-milliwave band of ultra high frequencies over 10 GHz. Any conventional ultra high frequency radio communication apparatus comprises a combination of circuit blocks made of component assemblies for both transmitter and receiver functions.
FIG. 1 illustrates an ultra high frequency device 1 of a fundamental type for use as a high-frequency high-power amplifier in such a conventional apparatus, in which one or more semiconductor chips C which act as a high-frequency high-power amplifier are installed in a package P. The package P has two feed through members T provided at both longitudinal ends thereof for input and output of signals of ultra high frequencies as extending outwardly of the package P. The feed through T is often used as a coaxial connector for connection of its package P. The ultra high frequency device 1 is coupled by a coaxial cable with a relevant connector or a high frequency printed circuit board to an antenna, an oscillator circuit, a frequency converter circuit, and others, thus constituting a transmitter and receiver combination.
FIG. 2 shows a transmitter module 2 which contains a semiconductor chip having functions of a plurality of the semiconductor chips C of the package device 1 illustrates in FIG. 1 and has the functions for transmission in a package P'. The transmitter module 2 includes, as shown in FIG. 3, a semiconductor chip C1 functioning as an oscillator circuit (OSC), a semiconductor chip C2 functioning as a modulator circuit, and a semiconductor chip C3 functioning as a power amplifier circuit (PA) in the package P'. Each of the semiconductor chips forms a circuit block having a particular function.
The semiconductor chips C1, C2, and C3 are shaped of substantially 2 mm square and installed in the package P' which serves as a shielding from the outside and has inner compartments defined by partitions extending from the side wall thereof. As the semiconductor chips C1, C2, and C3 are located in their respective compartments of the package P', they are joined to one another by coaxial members or microwave transmission lines hence creating the transmitter module 2. The receiver module including a low noise high frequency amplifier circuit (LNA) and a demodulator circuit may also be constructed by the same manner.
The shielding of each of the semiconductor chips C1, C2, and C3 from the other in the transmitter module 2 is designed for preventing interference between any two adjacent semiconductor chips and also, generation of cavity resonance on the carrier frequency caused by extension of the space. If the package P' has non of the partitions shown in FIG. 2 with the semiconductor chips all being located in a large single space, the generation of cavity resonance will possibly be increased.
FIG. 4 shows another type of the conventional transmitter module. The transmitter module 3 of FIG. 4 includes a semiconductor chip C1 of an oscillator circuit, a semiconductor chip C2 of a modulator circuit, and a semiconductor chip C3 of a power amplifier circuit joined in a cascade connection in a package P". The size of the semiconductor chips is 1.5 mm to 2 mm square. The semiconductor chip C3 is connected by a transmission line to the connector G of a wave guide of which output is joined to an antenna. Since loss in the wave guide is generally smaller than that in the transmission line, the output of circuit blocks in the transmitter module 3 can be transmitted with minimum loss from the wave guide to the antenna. The above construction is not limited to the transmitter but may be applied to the receiver module with equal success. In the receiver module of the same construction as of FIG. 4, semiconductor chips are connected from a voltage-controlled oscillator circuit (VCO) to a buffer amplifier circuit (BUF), a frequency converter circuit (MIX), and a low noise amplifier circuit (LNA) as shown in FIG. 5.
Although the semiconductor chips C1, C2, and C3 in the transmitter module 3 of FIG. 4 are not shielded separately, they may be operable as their overall dimensions are small enough.
The conventional devices or modules of the foregoing types are however unfavorable to satisfy serious requirements including downsizing and cost saving of the ultra high frequency radio communication apparatus, while every up to date electronic or electric apparatus is required to reduce its size to a minimum.
More particularly, the conventional device 1 shown in FIG. 1 carries only a part of the entire arrangement of a common radio communication apparatus and when it is used, the radio communication apparatus will be bulky in the size and costly to some extent.
The transmitter module 2 shown in FIG. 2 includes a plurality of devices similar to the device of FIG. 1 and allows the radio communication apparatus to be smaller in the size as compared with the use of the device of FIG. 1. The transmitter module 2 has however the semiconductor chips of different sizes shielded separately in its package which is thus maintained in a considerable size, hardly reducing the overall dimensions as well as the production cost. Also, the transmitter module 2 has to be joined to other modules including a receiver and an antenna with the use of bulky wave guides, coaxial cables, or high frequency circuit board, hence causing the radio communication apparatus to stay heavy.
The transmitter module 3 shown in FIG. 4 may be reduced to a smaller size than the transmitter module 2 of FIG. 2. However, the transmitter module 3 also has to be joined to other modules including a receiver and an antenna with the use of bulky wave guides, coaxial cables, or high frequency circuit board, hence contributing to the incomplete downsizing of the radio communication apparatus.